Controlling a flyback converter for use with a computer system

Abstract

The disclosed embodiments provide an apparatus that controls a flyback converter for use with a computer system. During operation, the apparatus senses an output voltage and output current of the flyback converter. The apparatus then switches a mode for controlling the flyback converter from a discontinuous mode to a continuous mode based on the sensed output voltage and the sensed output current.

What is claimed is: 
     
         1 . A method for controlling a flyback converter for use with a computer system, the method comprising:
 sensing an output voltage of the flyback converter;   sensing an output current of the flyback converter; and   switching a mode for controlling the flyback converter from a discontinuous mode to a continuous mode based on the sensed output voltage and the sensed output current.   
     
     
         2 . The method of  claim 1 , wherein controlling the flyback converter in the discontinuous mode involves controlling the flyback converter in a constant voltage mode. 
     
     
         3 . The method of  claim 1 , wherein controlling the flyback converter in the continuous mode involves controlling the flyback converter in a constant current mode. 
     
     
         4 . The method of  claim 1 , wherein switching the mode for controlling the flyback converter from the discontinuous mode to the continuous mode based on the sensed output voltage and the sensed output current involves switching the mode for controlling the flyback converter from the discontinuous mode to the continuous mode when the sensed output voltage is less than a predetermined voltage and the sensed output current is greater than a predetermined current. 
     
     
         5 . The method of  claim 1 , wherein a controller for controlling the flyback converter includes a continuous mode controller and a discontinuous mode controller, and switching the mode for controlling the flyback converter from the discontinuous mode to the continuous mode involves switching an output of the controller from an output of the discontinuous mode controller to an output of the continuous mode controller. 
     
     
         6 . The method of  claim 1 , further including:
 switching the mode for controlling the flyback converter from the continuous mode to the discontinuous mode based on the sensed output voltage and the sensed output current.   
     
     
         7 . The method of  claim 1 , further including:
 switching the mode for controlling the flyback converter from the continuous mode to the discontinuous mode after a predetermined time period.   
     
     
         8 . The method of  claim 1 , wherein a frequency of operation of the flyback converter in the continuous mode is higher than a frequency of operation of the flyback converter in the discontinuous mode. 
     
     
         9 . A non-transitory computer-readable storage medium containing instructions that, when executed by a processing subsystem in a controller, cause the controller to perform a method for controlling a flyback converter for use with a computer system, the method comprising:
 sensing an output voltage of the flyback converter;   sensing an output current of the flyback converter; and   switching a mode for the controller from a discontinuous mode to a continuous mode based on the sensed output voltage and the sensed output current.   
     
     
         10 . The storage medium of  claim 9 , wherein controlling the flyback converter in the discontinuous mode involves controlling the flyback converter in a constant voltage mode. 
     
     
         11 . The storage medium of  claim 9 , wherein controlling the flyback converter in the continuous mode involves controlling the flyback converter in a constant current mode. 
     
     
         12 . The storage medium of  claim 9 , wherein switching the mode for controlling the flyback converter from the discontinuous mode to the continuous mode based on the sensed output voltage and the sensed output current involves switching the mode for controlling the flyback converter from the discontinuous mode to the continuous mode when the sensed output voltage is less than a predetermined voltage and the sensed output current is greater than a predetermined current. 
     
     
         13 . The storage medium of  claim 9 , wherein:
 the controller includes a continuous mode controller and a discontinuous mode controller, and switching the mode for the controller from the discontinuous mode to the continuous mode involves switching an output of the controller from an output of the discontinuous mode controller to an output of the continuous mode controller.   
     
     
         14 . The storage medium of  claim 9 , further including:
 switching the mode for controlling the flyback converter from the continuous mode to the discontinuous mode based on the sensed output voltage and the sensed output current.   
     
     
         15 . The storage medium of  claim 9 , further including:
 switching the mode for controlling the flyback converter from the continuous mode to the discontinuous mode after a predetermined time period.   
     
     
         16 . The storage medium of  claim 9 , wherein a frequency of operation of the flyback converter in the continuous mode is higher than a frequency of operation of the flyback converter in the discontinuous mode. 
     
     
         17 . An apparatus for controlling a flyback converter for use with a computer system, comprising:
 a first controller configured to control the flyback converter in a discontinuous mode;   a second controller configured to control the flyback converter in a continuous mode; and   a control mode selection module coupled to the first controller and to the second controller, and configured to receive an output voltage of the flyback converter and an output current of the flyback converter, and to select a controller for the flyback converter from the first controller and the second controller based on the output voltage and output current.   
     
     
         18 . The apparatus of  claim 17 , wherein the first controller is further configured to control the flyback converter in a constant voltage mode. 
     
     
         19 . The apparatus of  claim 17 , wherein the second controller is further configured to control the flyback converter in a constant current mode. 
     
     
         20 . The apparatus of  claim 17 , wherein when selecting the controller for the flyback converter based on the output voltage and output current, the control mode selection module is configured to:
 select the second controller when the output voltage is less than a predetermined voltage and the output current is greater than a predetermined current.   
     
     
         21 . The apparatus of  claim 17 , wherein when selecting the controller for the flyback converter based on the output voltage and output current, the control mode selection module is configured to:
 select the first controller when the output voltage is greater than a predetermined voltage and the output current is less than a predetermined current.   
     
     
         22 . The apparatus of  claim 17 , wherein when the controller selected by the control selection module is the second controller and a predetermined time period has elapsed since the second controller was selected by the control selection module, the control selection module is further configured to select the first controller. 
     
     
         23 . The apparatus of  claim 17 , wherein the second controller is configured so that a frequency of operation of the flyback converter when controlled by the second controller is higher than a frequency of operation of the flyback converter when controlled by the first controller.